Gale Crater Stereo CTX DTMs + Orthoimages

<b>CTX Stereo Digital Terrain Models (DTMS) and Orthorectified Images</b> See Readme for full details.<br> These data products were produced by Peter Grindrod and Joel Davis at the Natural History Museum, London. They are shared here in an "as is" format. Please read the following information carefully. <b>Data Structure</b> The file "Index_ DTMs.xlsx" gives the image numbers and DTM filenames. <b>Data Sets</b> The exact products for each image pair include: - 20 m/px DTM - 20 m/px FOM (Figure of Merit - see below) - 6 m/px orthoimage Each image has been orthorectified using the relevant DTM. No data have been georeferenced to either another data set in this release, nor another Mars data set. Therefore care should be taken in the first instance in georeferencing as required. Although each DTM is tied to MOLA, there are likely to be some small elevation steps across DTM boundaries as a result of no bundle adjustment across DTMs. Finally, the quality of the DTMs is on the whole good, but noise levels vary – check the FOM and create a hillshade to ensure that each DTM is adequate for required use. <b>DTM Vertical Precision</b> The vertical precision of the DTMs can be estimated by using the method outlined in: - Kirk, R. L., E. Howington-Kraus, B. Redding, D. Galuszka, T. M. Hare, B. A. Archinal, L. A. Soderblom, and J. M. Barrett, (2003), High-resolution topomapping of candidate MER landing sites with Mars Orbiter Camera narrow-angle images, <i>J. Geophys. Res.</i>, 108(E12), 8088, doi:10.1029/2003JE002131. - Kirk, R. L., et al. (2008), Ultrahigh resolution topographic mapping of Mars with MRO HiRISE stereo images: Meter-scale slopes of candidate Phoenix landing sites, <i>J. Geophys. Res.</i>, 113, E00A24, doi:10.1029/2007JE003000. <b>File Format</b> Each file is available in geotiff format. <b>Credit</b> CTX images should be credited "Image: NASA/JPL-Caltech/MSSS” Derived DTMs should be credited as "DTM: NASA/JPL-Caltech/MSSS/NHM”, and as follows, if possible "The stereo DTM processing was carried out at the Natural History Museum, London" <b>Figure of Merit (FOM) explanation</b> If present, the FOM is a data product produced by the BAE Systems SOCET SET software, which is essentially a measure of the quality of the DTM. The numerical value of each pixel corresponds to either how the pixel was generated or the confidence in the value.<br>**CTX立体数字地形模型（Digital Terrain Models，DTMS）与正射校正影像** 完整细节请参阅自述文件（Readme）。 本数据集由伦敦自然历史博物馆（Natural History Museum）的Peter Grindrod与Joel Davis制作，以「现状提供（as-is）」的形式共享于此。请仔细阅读以下说明。 **数据结构** 文件「Index_ DTMs.xlsx」中包含影像编号与DTM文件名。 **数据集内容** 每一组影像对对应的完整数据产品包括： - 20米每像素的DTM - 20米每像素的品质因子（Figure of Merit，FOM，详见下文） - 6米每像素的正射影像 所有影像均已通过对应DTM完成正射校正。本数据集内未对任何数据进行跨数据集地理配准，亦未与其他火星数据集完成地理配准，因此如需进行地理配准，请务必先谨慎处理。尽管所有DTM均已与火星轨道激光测高仪（Mars Orbiter Laser Altimeter，MOLA）数据绑定，但由于未对不同DTM进行跨区域光束法平差，DTM边界处可能存在小幅高程跳变。总体而言，DTM的整体质量尚可，但噪声水平存在差异——请务必核查FOM数值并生成地形晕渲图（hillshade），以确认该DTM是否满足您的使用需求。 **DTM垂直精度** DTM的垂直精度可通过下述文献中提及的方法进行估算： - Kirk, R. L.、E. Howington-Kraus、B. Redding、D. Galuszka、T. M. Hare、B. A. Archinal、L. A. Soderblom及J. M. Barrett（2003）：《利用火星轨道相机窄角影像对火星探险漫游者候选着陆点开展高分辨率地形测绘》，《地球物理学研究杂志》（*J. Geophys. Res.*），108(E12)，8088，DOI:10.1029/2003JE002131 - Kirk, R. L.等（2008）：《利用火星勘测轨道飞行器高分辨率成像科学实验（Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment，MRO HiRISE）立体影像开展火星超高分辨率地形测绘：凤凰号候选着陆点的米级坡度》，《地球物理学研究杂志》（*J. Geophys. Res.*），113，E00A24，DOI:10.1029/2007JE003000 **文件格式** 所有文件均采用GeoTIFF格式。 **引用声明** CTX影像的引用格式为：「影像来源：NASA/JPL-Caltech/MSSS」；衍生DTM的引用格式为：「DTM来源：NASA/JPL-Caltech/MSSS/NHM」，若条件允许，请补充标注：「本立体DTM处理工作由伦敦自然历史博物馆完成」。 **品质因子（Figure of Merit，FOM）说明** 若数据中包含FOM，则其为BAE Systems公司SOCET SET软件生成的数据产品，本质上是DTM质量的量化评估指标。每个像素的数值对应其生成方式，或是该像素数值的置信度。